The invention relates generally to systems and methods for metal casting, and more specifically to systems and methods for high temperature die casting.
Certain metals and alloys have previously responded better to pressurized die casting while others are better cast using investment processes. Lower melting temperatures of aluminum-based and magnesium based alloys, for example, as well as favorable solidification pathways permitted the use of temperature resistant injection molds whereby the molten metal is solidified with a minimum of shrinkage or defects. Alloys with higher melting temperatures such as titanium-based, nickel-based, and cobalt-based alloys and superalloys have traditionally been investment cast.
Attempts to die cast higher temperature alloys have been often thwarted due in part to the difficulty in finding suitable materials for casting dies that could withstand the necessary temperatures and pressures. Even when a suitable casting die material is available, the alloy cannot be superheated far above its melting temperature without compromising the die. This offers a much smaller margin of error and a narrower temperature range available for solidification. As a result, traditional pressurized die castings using these high temperature alloys frequently have excessive defects including shrinkage and knit lines, also known as cold shuts. Most of these defects then result in scrapping out the casting, unnecessarily costing time, effort, and money to recycle and recast the parts until a suitable casting is finally formed.